If you have enough metal to build something but not enough rads, you will only build it as fast as you have the rads to support it. The hyper specific mathematics of that I don't know and I don't really see why it matters.

I'm thinking this might all matter in having a better understanding of what will produce, how quickly, in what order -- and whether there is actually such a thing as sub-optimal production speed.

OK, so a few more questions to clarify:

1) I'm hearing you say that each "tick" of production might require a certain amount of metal, and a certain amount of rad; and if you are lacking either one (let's say rad), then... what??? There would be no tick? Or there would be a fractional tick, such that metal would be consumed proportional to the rad???

2) What happens to the available metal that can't be provisioned to construction, due to rad shortage? Is it assigned to another production building, or does it go into storage, or something?

3) Would it be correct to assume that when you don't have enough resources, the amount that you do have is distributed equally?

4) Is there a priority order to the way that resources are provisioned to production buildings? Ex. Do armories get resources before factories?

I'm thinking this might all matter in having a better understanding of what will produce, how quickly, in what order -- and whether there is actually such a thing as sub-optimal production speed.

OK, so a few more questions to clarify:

1) I'm hearing you say that each "tick" of production might require a certain amount of metal, and a certain amount of rad; and if you are lacking either one (let's say rad), then... what??? There would be no tick? Or there would be a fractional tick, such that metal would be consumed proportional to the rad???

2) What happens to the available metal that can't be provisioned to construction, due to rad shortage? Is it assigned to another production building, or does it go into storage, or something?

3) Would it be correct to assume that when you don't have enough resources, the amount that you do have is distributed equally?

4) Is there a priority order to the way that resources are provisioned to production buildings? Ex. Do armories get resources before factories?

1) Fractional. You'll only work to 80% the speed if you only are producing 80% of the required resource.

2) It goes in to storage, unless utilized by a different unit/building. If you would ordinarily produce five metal and eight rads, and are building a unit that demands five metal and ten rads, you'll end up with a one metal income.

3) I'm not sure what you mean, but if you're asking if all demands split the load, then yes.

4) As far as I'm aware, every single source takes its exact demand perfectly even. If you have five times the amount of demand of a resource, spread through five different queues, they'll each slow to 20% the default speed. If you have ten times the amount of demand spread through three different queues, they'll each slow to 10% the default speed.

In general, it's not the worst thing to run a negative income (After all, any resources gained when you're at max capacity are completely wasted), with a few exceptions:

1) Splitting your economy down to extremely slow fractions makes for a very uneven production. While your overall production of units/hour won't change much if at all, you might find yourself producing no units for several minutes at a time, which is dangerous.

2) As a Substrate player you can bank resources indefinitely, so there's not quite as much benefit to spending resources now that could be better used later.

3) In general, foresight can let you plan to use your resources a bit more evenly. Instead of banking up five rad-heavy builds at once, it can be far more effective to do two rad-heavy builds, two-metal heavy ones and a balanced one. Doing so will minimize the amount of slowdown, and minimize the amount of wasted materials.